Gaseous electric discharge device



May 14, 1940.

GASEOUS ELECTRIC DISCHARGE DEVICE Filed April 30, 1935 INVENTOR W f d ATTORNEY E. G. DORGELO 2,2GO,950

Patented May 14, 1940 GASEOUS ELECTRIC DISCHARGE DEVICE Eduard G. Dorgelo, Eindhoven, Netherlands, assig-nor to'General Electric Company, a corporation of New York Application April 30,1935, Serial No. 19,086

. In Germany May 3, 1934 2 Claims.

The present invention relates to gaseous electric discharge devices generally and more particularly theinvention relates to such devices the containers of whichare atan elevated temperature dur- 5 ing the operation of the device, such as high pressure mercury vapor lamps and lamps the gaseous atmosphere of which consists of or comprises the vapor of a diflicultly vaporizable metal, that is, a metal which is at a pressure of less than 1 mm. at a temperature of 200 0., such as sodium, cadmium, magnesium, or zinc.

I have observed that at the high container temperatures characteristic of siich lamps during the operation thereof the glass wall of the con- 1 tainer is electrically conducting and that, when an auxiliary electrode is mounted in contact with' the container wall, electrolysis takes p12 ce at the contact points between the container and the auxiliary electrode. The current flowing through 0 the container glass at the contact points softens the glass which terminates'the life of the lamp.

The object of the present invention is to provide a long lived gaseous electric discharge lamp device the container of which is at an elevated 25 temperature during the operation of the device and which container has an auxiliary electrode associated therewith. Still further objects and advantages attaching to the device and to its use and operation will be apparent to those skilled 30 in the art from the following particular description.

The invention attains its object by interposing between the auxiliary electrode and the wall of the container a body of material which is a good 35 electrical insulator even at the high container temperatures. In one embodiment of the invention at least the part of the auxiliary electrode in contact with the container wall is covered with an insulating enamel. When desired the auxiliary an electrode consists of a metal the oxide of which Like numbers denote like parts in both thefigures. 66 Referring to the drawing the new and novel gaseous-electric discharge lamp comprises a U- shaped container I having an electrode 2 sealed into each end thereof and having a gaseous atmosphere therein comprising starting gas, such as neon at a low pressure of approximately 1 to 5 mm., and a metal vapor, such as sodium vapor.

A quantitycf sodium is introduced into said container I during the manufacture of the lamp. which acts as the source of the sodium vapor. Said electrodes 2 are electron emitting when 10 heated and comprise a heater element, such as a coiled tungsten filament having another tungsten or nickel filament wrapped around said coiled filament, coated or impregnated with an electron emitting material, such as barium oxide. In 16 order to obtain an effective metal vapor pressure in the lamp during the operation thereof the container I must be at an elevated temperature. A heat conservator, such as a double-walled jacket having the space between the walls thereof evacugo ated, which reduces heat losses from said container I and-in which said container I is removably mounted is useful in this connection.

- The lamp has an auxiliary electrode consisting of an element 3, of nickel, for example, in eontact with said container I at the curved part thereof and a narrow metal strip 4 extending along said container I between the parallel legs thereof. The element 3 partially surroundsthe curved part of the container I and is covered with an electrically insulating enamel layer 5, such as aluminium oxide or magnesium oxide, so that said element 3 is separated from the container I. The strip 4 is connected to a current lead of one of the electrodes 2 so that the auxil- I iary electrode is at the same potential. as the main electrode 2. When desired, the auxiliary electrode is at a different potential than said main electrode 2. When desired, the strip 4 is likewise covered with insulating enamel and is mounted 40 along the container I. Softening of the container- I at the partsthereof covered by the element 3 and the strip 4 doesnot take place in the above described lamp. When desired, the strip 4 and v the element 3 consist ofaluminium the surface of which is oxidized.

While I have shown and described and have pointed out in the annexed claims certain novel features of the invention, it will be understood that various omissions, substitutions and changes in the forms and details of the device illustrated and in its use and operation may be made by those skilled in the art without departing from the broad spirit and scope of the invention, for

example, when desired, the element 3 is uncoated o6 auxiliary electrode is a wire wound around the container which wire is covered with insulating j material, and, when desired, the surface o1 the wire is oxidized and is of a material the oxide of which is insulating.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1.} '1. An electric discharge device comprising a U-shaped container, electrodes sealed therein at the ends thereof, a gaseous atmosphere therein, an external auxiliary electrode mounted on the curved part of said container and a layerof insulating material interposed between said auxiliary electrode and said container.

2. An electric discharge device comprising a U-shaped container, electrodes and electrode leads sealed therein at the ends thereof, a gaseous atmosphere therein, an external auxiliary electrode mounted on the curved part of said container, a layer of insulating material interposed between said auxiliary electrode and said container and a current lead connecting said auxiliary electrode to one of said electrode leads.

' EDUARD G. DORGELO. 

